Circuit: User-Friendly Digital Sound Effects Generation

Would you like to construct your own sound effects unit? Check out this circuit from 2010, which was built around an innovative effects chip. Equipped with an intelligent user interface, the unit could deliver reverb, chorus and flanger effects.
 

Generate Sound Effects

The user-friendly design featured a few handy features: an LCD, an EEPROM for holding eight supplementary, effect algorithms, a ramp generator for attack and decay effects, 64 preset profiles for user-defined effect settings, and a MIDI interface.
  An ATmega microcontroller controlled the effects processor IC via four digital lines and three analog lines. The user interface had its own microcontroller. The LCD module was operated in 4-bit mode, and connector K2 was connected to K3 on the main board. Refer to the nearby schematic diagram of the main board, with the buffer amplifiers for the signal inputs and outputs and the digital potentiometers for dry/effect mixing shown on the left. The three resistor/capacitor networks in the middle of the diagram convert 5-V PWM signals into DC control voltages with a range of 0 to 3.3 V.

"The audio signals from the input connectors are fed directly to the inputs of the FV-1 IC via coupling capacitors, and to the inputs of the buffer amplifiers for dry/effect mixing (IC1a and IC1b)," the author Hubert Bollig explained. "The outputs of IC1a and IC1b are fed to the inputs of the electronic potentiometers (X9C503). The output signals of the effect processor are fed to the other inputs of the digital potentiometers. The signals from the potentiometers pass through buffer amplifiers on their way to the output connectors."

More About the Attenuator
Want to learn more about Bollig's Digital Multi-Effects Unit featuring 15 configurable sound effects and a user-friendly HMI? The article appeared in the 09-2010 edition of Elektor. Elektor Members enjoy an ElektorMag subscription, an Elektor Store discount on most products, and access to Elektor’s online library, which includes this article and countless others. Take out a membership today!